Which of the following is not a type of addition polymerisation?

Polycondensation polymerisation

The correct answer is option 2. Polycondensation polymerisation

Polycondensation polymerisation is not a type of addition polymerisation; it is a different polymerisation mechanism altogether. Addition polymerisation involves the successive addition of unsaturated monomers to form a polymer without the formation of any by-products, while polycondensation polymerisation involves the elimination of small molecules such as water, alcohol, or HCl during polymerisation.

Let us briefly discuss each option to clarify:

1. Free radical polymerisation: Involves the initiation, propagation, and termination of chain growth through the action of free radicals. It is a type of addition polymerisation commonly used for the synthesis of polymers like polyethylene and polystyrene.

2. Polycondensation polymerisation: Involves the condensation reaction between monomers with two or more functional groups, resulting in the formation of polymer chains along with the release of small molecules like water or alcohol. Examples include the synthesis of polyesters, polyamides, and phenol-formaldehyde resins.

3. Anionic polymerisation: Involves the initiation and propagation of polymer chains through the action of anionic species (negatively charged ions). It is a type of addition polymerisation used for the synthesis of polymers like polybutadiene and polyisoprene.

4. Cationic polymerisation: Involves the initiation and propagation of polymer chains through the action of cationic species (positively charged ions). It is another type of addition polymerisation used for the synthesis of polymers like polypropylene and polyvinyl chloride (PVC).

Among the options provided, polycondensation polymerisation is the process that is not a type of addition polymerisation. It involves the elimination of small molecules during polymerisation, unlike addition polymerisation, which does not involve the loss of any atoms or molecules.